Vibrating screen



4, 1941' J. A. TRAYLOR ETAL 2,230,314

VIBRATING SCREEN Filed June 7, 1957 2 Sheets-Sheet 1 JLH E I a INVENTORS JU/M ,4. 7164710? Jfl/M/ 5. TFAYZOZ.

2 Sheets-Sheet 2 Feb. 4, 1941. J. A. TRAYLOR ETAL VIBRATING- SCREEN Filed June 7, 1957 Patented Feb. 4, 1941 UNITED STATES PATENT OFFICE VIBRATING SCREEN John A. Traylor and John B. Traylor, Denver, 0010.; Edna '1. Eisenhand, Tessie S. Traylor and John B. 'lraylor co-executors of estate of John A. Traylor, deceased Application June 7, 1937, Serial No. 146,717

4 Claims.

rating or concentrating of ores, crushed rock or similar material, and which may be adapted to other uses, the characteristic feature of the motion being that a motion is produced in the continuous path at given speeds in certain directions and at other speeds in other directions throughout the path.

In adapting our invention to screens'of the character employed for screening, classifying and otherwise treating ores, crushed rock and similar substances, an elongated box-like structure is employed having a wire mesh or similar screen surface material disposed throughout the area enclosed by the box, one end, of the box-like structure constituting the entrance end at which the material enters the screen, and the opposite end of which constitutes an exit end from which the rejected material, or material too large to pass through the meshes of the screen, will pass out of the box-like structure, the material being advanced from the entrance to the exit end of the screen by the vibration or gyratory motion of the screen surface. The box-like structure is usually mounted upon a base frame and the vibration or gyratory motion is produced by coupling the screen member to eccentric mechanism, which when rotated will swing the screen memher through its desired path of movement.

In screens of this character operating by means of eccentrics, the screen surface travels through a circular path which includes an upward and forward movement and a downward and rearward movement, at a substantially uniform rate of motion throughout the cycle, the material being advanced along the screen by reason of its inability to follow exactly the motion of the screen surface due to the inertia of the material. The material therefore travels across such screen surface at a relatively low rate unless the screen surface is disposed at a considerable angle to the horizontaL. which requires considerable head room in the building or other location where such screen is to be used.

It is therefore an object of our invention to.

provide a screen of the character set forth herein in which the movement of the screen surface through its circular path of travel is achieved at one rate of speed while traveling through one portion of the path of travel and at a different rate of speed .while traveling through other portions of the path to achieve a greater throwing of the material from the screen surface and a more rapid rate of advance of the material along the screen surface for each movement of the screen through its circular path.

Another object of our invention is to provide a screen of the character set forth wherein an eccentric drive may be used for moving the screen surface through its circular path and in which means is provided for progressively accelerating 10 the movement of the screen surface through selected portions of its path of travel in such manner as to increase the amount of throw of the materialupwardly and forwardly or to increase. the amount of rearward movement of the screen surface while the material is in suspension above the screen surface.

Another object of -our invention is to provide a screen of the character set forth wherein resilient means is employed to assist the action of 0 ,a rotating power mechanism to progressively accelerate'the motion of the screen surface during portions of the cycle of its operations.

Another object of our invention is to provide a screen of the character set forth wherein the 20 tension means applies its forces to accelerate or decelerate the motion of the screen during dif ferent portions of its cycle of operations along such planes or during such portions of the cycle as will advance the material along the screen 30 surface at a relatively high rate.

Other objects of our invention will be apparent from a study of the following specification, read in connection with the accompanying drawings, wherein- 35 Fig. 1 is a vertical sectional view of a screen embodying our invention, the section being taken along line I-I of Fig. 2;

Fig. 2 is an end elevational view of the screen shown in Fig. 1, looking in the direction of the 40 arrows 11-11 of Fig. 2;

Fig. 3 is an end elevational view similar to Fig.

2 but illustrating a modified form of tension means which may be employed in the practice of our invention; 45

Fig. 4 is an end elevational view similar to Figs.

2 and 3 but illustrating a still further modified form of our invention, employing a 4-point. suspension for the screen;

Fig. 5 is a fragmentary vertical sectional view 50 of one of the bearing brackets and eccentric members which may be employed in the form of the invention illustrated in Fig. 4, taken along V-V of Fig. 4;

Fig. 6 is a fragmentary end view of a still fur- 55 ther modified form of our invention, similar to Fig. 4 but illustrating a modified form of tensio member which may be employed; and

Fig. 7 is a diagrammatic view illustrating the.

I The rear wall 4 is preferably angled rearwardly to assist'in guiding materialinwardly of the boxlike structure as it is dumped into the box-like structure at the left-hand end thereof, as viewed in Fig. 1. At a considerable distance above the bottom or floor 5 of the box-like structure, a sheet of screen surface material 6 is stretched, preferably covering the entire area enclosed by the walls 2, 3 and 4 and constituting a screen surface over which the material to be screened will be advanced from the entrance or left-hand end of the screen toward the exit or right-hand end thereof, the screen surface material being secured in any suitable manner as to a bracket I at the deft-hand end of the screen and by means of rods or hooks 8 secured at the right-hand end thereof. Near the exit or right-hand end of the screen we provide a structural member 9 extend: ing across the live screen I between the walls 2 and 3, this member being preferably of angular cross section, one leg III of which may have an upturned flange I I to which the hooks or rods 8 may be secured while the opposite leg I2 of which extends downwardly and through the floor 5 of the live screen I to prevent the material which passes through the meshes of the screen from passing out of the exit end or open end of the live screen I. The live screen I is supported upon a base or base frame I3 which may be constructed in any suitable manner though we prefer to construct the same with a pair of side rails I4 and I5 extending longitudinally relative to the live screen I on opposite sides thereof, the side rails I4 and I5 being interconnected near their ends by a pair of cross rails I6 and I1. While the shape of the rails I4, I5, I5 and I1 may be made of any suitable structural steel shapes, we prefer to employ T shapes as illustrated herein in order to provide a relatively large upper surface on the rails for the purpose of mounting bearings, motors and other devices, as will be more fully described hereinafter. The live screen I is mounted upon the base frame I'3 by means of a plurality of bracket members It, in the form of the invention illustrated in Figs. 1 and 2, such bracket members being disposed at opposite ends of the live screen I, preferably along the longitudinal center line of the'live screen I. The brackets I8 are preferably secured directly to the underneath side of the live screen I as by means of bolts I9 and each of the brackets I8 includes the downwardly and rearwardly depending portion split as indicated at 20 to form a bearing housing having complementary halves 2I and 22 within which is mounted a roller bearing 24. The roller bearing 24 is in turn mounted upon an eccentric 25 secured to or forming an integral part of a power shaft 26 which is in turn journaled in a pair of bearing brackets 21 and 28 mounted upon the top web of one of the cross rails I6 or II. It will be understood by those skilled in the art that the brackets I8 at 2,230,814 opposite ends of the live screen I are identical in construction and the detailed description of one of these brackets will suffice as a description for both.

While the shaft 26 may be rotated by any suitthe bracket I 8, causing this bracket to describe a circular path of movement and in turn the live screen I will move in a circular path of movement, each revolution of the shaft 26 prc'iucing a cycle of movement which includes an upward and forward movement of the screen surface 6 and a rearward and downward movement of the screen surface 6.

By referring particularly to Fig. 7, it will be observed that rotation of the power shaft 26 will cause the eccentric 25 todescribe a circular path indicated by the dottedcircle A, which path will also be described by the surface of the screen 6. Shaft 26 is rotated in a clockwise direction as by means of the motor 29, the effect of gravity upon the mass of the screen I and the material contained therein willbe such as to accelerate the movement of'the eccentric during that portion of its cycle of rotation which lies on the right-hand side of a line B extending normal to the surface of the screen 6 and'will cause a; deceleration or a retarded movement of the eccentric 25 as it passes through theother half of its cycle of operations on the left-hand side of the normal line B. However, this change of rate will occur only while the material to be screened is in contact with the surface of the screen 6.

We have discovered that it is advantageous in the screening of the material, as well as in the advancing of the material along the surface of,

the screen, to accelerate the motion of the eccen-' tric during the upward and forward movements of the screen to give the material an upward and forward thrust or throwf at a greater rate than would be possible if the eccentric were permitted to travel at a uniform rate of speed. on the other hand, in the screening of certain types of material, it might be equally advantageous to rapidly accelerate the motion of the eccentric during the downward and rearward portions of the movement of the screen surface, such acceleration exceeding gravity acceleration so that the screen surface will be dropped out from below the -material thereon and will be swung rearwardly while this material is still in suspension. In either event the amount of forward throw" of the material or advance of the material along the screen per rotation of the eccentric 25 will be greatly increased.

We achieve these desirable results by providing a tension means acting upon the eccentric together by means of bolts 34. The split housing 33 surrounds and engages the central portion of a tension rod 35 which extends between and has each of its ends secured to the longitudinal rails I and I5 of the base frame I3. The tension rod 35 constitutes in effect a spring held at each of its ends under any desired tension by extending the threaded ends 38 of the rod 35 through the rails I4 and I5, the rod 35 being drawn taut therein by means of suitable nuts 31. The rod 35 is illustrated as having its longitudinal axis disposed rearwardly and below the axis of rotation of the shaft 26 so that a plane intersecting the axis of the rod 33 and the axis of the shaft 26 will extend upwardly and forwardly relative to the live screen I. I

By referring particularly to Fig. 5,-it will be noted that as the eccentric rotates from the full line position shown in Fig. 7 downwardlyand rearwardly, the central portion of the tension rod 35 will be swung downwardly and rearwardly until the eccentric 25 passes the plane intersecting the rod 35 and the shaft 26. Then the tension of the rod 35 will tend to restore this rod to its original location shown in full lines in Fig. 7 and in so doing willimpart a progressively increasing acceleration to the motion of the eccentric until the eccentric 25 arrives again at its full line position as shown in Fig. '7, at which point the effect of the eccentric riding in the eccentric strap formed by the housing halves 2| and 22 will stop any further upward thrust on the part of the tension rod 35. 'However, due to this accelerated upward and forward motion, the material on the screen surface will be flung upwardly from the screen surface and forwardly thereof at a rate greater than the normal rate at which it would be thrown under uniform rotation of the eccentric 25. The material will therefore be thrown forwardly a greater distance in advance than would be possible without the use of the tension rod 35. Now the movement of the eccentric 25 to the next half of its cycle of operations on the right-hand side of the plane indicated by the arrow C will be somewhat retarded since at this time the rod 35 must be again distorted from its normal neutral or rest position and as the eccentric again passes into the next half of the cycle of operation on the left-hand side of the plane C, as viewed in Fig. '7, another acceleration impulse will be given to it.

In the screening of certain types of material,

best results are obtained by accelerating the eccentric on the right-hand side of the plane C and for this purpose we prefer that the normal or rest position of the tension rod 35 shall occur when the eccentric is in the upper right-hand quadrant of its movement. However, for the screening of other types of materials it appears best that the tension rod shall have its neutral or rest position when the eccentric 25 is in the lower left-hand quadrant of its rotation, thus causing the distortion of the tension rod away from its rest position during the upward and forward movement of the screen surface 6 but accelerating the downward and rearward movement so as to leave the material suspended in the air while the screen surface is retracted.

In any event, the essential feature appears to be in applying a spring force or tension medium to exert a force accelerating the rotation of the eccentric in a plane which extends at an acute angle to the plane of the screen surface, the plane C extending through the axis of the rod 35 and the axis of the shaft 26 inclining upwardly relative to the screen surface in the desired direction of movement of the-material over the screen surface, and such arrangement greatly increases the screening action above that which has been heretofore possible with screens of this character. Y

The tension means employed to impart the accelerated motion should be of such size and such strength that it can support the weight of the .live screen I and the load of material placed therein without flexing so that the entire force required to flex or distort the tension means will be applied by the eccentric 25 and the entire restoring'force exerted by the tension means will beappliedto an acceleration of the eccentric 25.

While the straight tension rod 35 illustrated in Figs. 1 and 2 constitutes a simple and ready means for applying the desired acceleration forces, such straight rod is limited to the distance through which it can be moved and hence the stroke of the screen is limited. To increase the length of stroke or, in other words, the diameter of the circle A described by the eccentric 25, we may employ a tension rod such as that illustrated in Fig. 3 at 35a, this tension rod being constructed from a rod twisted into a helix of relatively great pitch and having its ends secured to the opposite longitudinal rails l4 and [5 of the base frame I3 in the same manner as described for the rod 35 in Figs. 1 and 2. It will be apparent from an inspection of Fig. 3 that a tension rod of this character may be flexed through a greater distance than would be possible with the construction shown in Figs. 1 and 2. In Figs. 1, 2 and 3 We have illustrated the suspension of the live screen I at only two points and these disposed along the longitudinal center line of the live screen I. The same principle, however, is adaptable to a 4-point suspension of the live screen I, as is illustrated particularly in Figs. 4 and 5 thereof, wherein the live screen I has at each of its four corners a bracket |8a which may include housing members 2! and 22 for enclosing the roller bearing 24 and the eccentric 25. The two brackets l8a at one end of the screen may be actuated by eccentrics 25 mounted upon a pair of aligned power shafts 26a, corresponding in all respects to the power shaft 26 heretofore described, but which in this instance will be coupled as by couplings 3|a to opposite ends of the shaft 30a of a motor 29a.

mounted upon the base frame I3a between the brackets l8a.

In this form of the device four tension rods 351) (only two of which are illustrated) may be employed, one for each of the brackets l8a, one end of each of these rods 35b being clamped in a bracket 40 mounted upon the base frame l3a while the opposite end of the tension rods 35b may be clamped in a split housing 33a connected to or forming an integral part ofthe brackets l8a. Again the rods 35b, like the rods 35 and 35a, must be selected of such size and strength that they will support the weight of the screen I and its load without flexing. Again it will be noted from an inspection of Fig. 5 that a plane drawn through the axis of rotation of the shaft 26a and the longitudinal axis of the rod 35b will be disposed atan acute angle to the-normal to the screen surface 6 and will extend in the direction of movement of the material over the screen surface so that the effect of the tension rods 35b will be to produce an acceleration of the eccentric 25 duringthat portion of its cycle of operations as will throw the material forwardly along the screen surface.

iii)

In Fig. 6 we have illustrated the adaptation of a short helically wound tensionrod No in place of the straight rods 35!) when a greater vided means for increasing the effectiveness of a screen by accelerating the motion'of the screen during those portions of its cycle of operations which tend toadvance the material forwardly along the screen surface. It will also be noted that by employing our tension means, consist ing of accelerating the eccentric in portions of its movements, a greater throw of the material above the screen surface may be also accomplished, which will assist materially in increasing the efliciency of the screen. Also it will be noted that while we have illustrated our tension means as comprising a tension rod, it will be equally apparent that other forms of spring mechanisms could be used, the essential characteristic being that the springs must be so constructed and so mounted as to exert their acceleration forces at an acute angle to the plane of the screen surface and extending in such direction that the apex C of the angle formed between the plane C and the plane 6 of the screen surface will be directed forwardly or in the direction of movement of the material over the screen.

It will be noted that .while we have shown only one spring or tension rod per eccentric, it will be apparent that several rods or springs may be associated with each eccentric where the load is such that a single spring would not be adequate.

While we have shown and described the preferred embodiment of our invention, we do not desire to be limited to any of the details of construction shown or described herein, except as defined in the appended claims.

We claim:

1. In a shaking screen construction, a screen member having a screen surface over which ma terial to be screened may pass, a base frame for supporting said screen member, power means on said base frame including a rotating shaft, an eccentric and an eccentric strap connected to said screen for moving said screen surface in a circular path through repeated cycles of operation, a resilient rod disposed on said base frame and extending parallel to said powershaft, means connecting said rod to said screen member, the axis of said rod and the axis of said shaft being disposed in a plane inclined upwardly relative to the screen surface in a desired direction of movement of the material over said screen surface.

2. In a shaking screenconstruction, a screen member having a screen surface over which material to be screened may pass, a base frame for I being disposed in a plane inclined upwardly rela-' tive to the screen surface in the desired direction of movement of the material over said screen surface to impart an accelerating thrust to said power means during one or more portions of each cycle of operations of said screen.

3. In a shaking screen construction, a screen member having a screen surface over which ma terial to be screened may pass, a base frame for supporting said screen member, power means on said base frame including a rotating shaft, an eccentric and an eccentric strap connected to said screen for moving said screen surface in a circular path through repeated cycles of operation, a resilient rod secured to and extending across said base frame in a direction parallel to the direction of said power shaft, means interconnecting said screen member and the center of said rod, the axis of said rod and the axis of said power shaft being disposed in a plane inclined upwardly relative to the screen surface in the desired direction of movement of said material over said screen.

4. In a shaking screen construction, a screen member having a screen surface over which material to be screened may pass, a base frame, means on said base frame mounting said screen member for movement in a vertical plane about a closed circular path and for maintaining a fixed angular relation between said screen surface and said base frame during said movement, power means secured to said base frame and including a rotating shaft, means connecting said power means to move said screen member about said circular path, a resilient rod disposed on said base frame and extending parallel to the axis of said shaft, and means connecting said rod to said screen member, the axis of said rod and the axis of said shaft being disposed in a plane inclined upwardly relative to the screen surface in a desired direction of movement of the material over said surface.

JOHN A. TRAYLOR.

JOHN B. 'I'RAYLOR. 

